From the US census bureauJobs are valued financially based upon their financial worth. That's not determined by men at random.
Money isn't the only way to determine the pros and cons of a job, either.
Working less hours, having less pressure and having flexibility is clearly seen as desirable, but don't factor into the wage gap.
The idea that some jobs have been historically done by men and are therefore more highly valued is backwards, in my opinion.
Men did the important jobs and women weren't allowed to. This was clearly wrong, but that's how it was.
Maybe I'm wrong, but I can't think of any careers that don't follow that pattern.
"In 2011, 9 percent of all nurses were men while 91 percent were women. Men earned, on average, $60,700 per year, while women earned $51,100 per year."
So even in traditionally female occupations, men somehow contrive to do better